The existing capacitive touch control technology is derived from the equation
                              V          =                                    I              ×              T                        C                          ,                            [                  Eq          ⁢                      -                    ⁢          1                ]            which indicates that the voltage V generated by charging a capacitance C with a constant current I in a fixed period of time T can be used to detect variation in the capacitance C. In a capacitive touch control device, conventionally, the sensed signal by sensing the capacitance C is an analog signal and is always converted into a digital signal for data calculation and processing, whose value is typically called ADC value and is linearly related to the sensed capacitance C. A capacitive touch control device has a basic capacitance Cb, and when nothing touches the capacitive touch control device, the charging process will produce a voltage
                    V        =                                            I              ×              T                        Cb                    .                                    [                  Eq          ⁢                      -                    ⁢          2                ]            When a finger touches the capacitive touch control device, the finger can be viewed as another capacitance Cf shunt to the basic capacitance Cb, and thus the same charging process will produce a voltage
                              V          ′                =                                            I              ×              T                                      Cb              +              Cf                                .                                    [                  Eq          ⁢                      -                    ⁢          3                ]            Since the voltages V and V′ are different from each other, the ADC values obtained in these two cases will be different from each other, too, and this difference can be used to identify whether a finger touches the capacitive touch control device. A conventional two-dimensional capacitive touch control device has touch sensors in two orthogonal directions, e.g. X and Y directions, to be sensed for variation in capacitance and thereby can identify the position of a finger on the touch plane.
However, when two or more fingers touch a two-dimensional capacitive touch control device, for example as shown in FIG. 1, the waveform established by the ADC values in the X direction may have only an identified peak, for example as shown in FIG. 2, if fingers 10 and 12 are very close to each other in the X direction and thereby produce an overlapped and indistinguishable waveform. Since the two touch points 16 and 18 can not be distinguished in the X direction, they will be identified as having a same X coordinate, and thus the calculated X coordinates for the fingers 10 and 12 will not be the actual positions of the fingers 10 and 12. Such waveform overlapping often occurs in multi-touch operation.
Therefore, it is desired a waveform dividing method for a capacitive touch control device to improve the positioning performance of the capacitive touch control device.